Vibronic Coupling in Semi-Fluorinated Alkanethiol Junctions: Implications for Selection Rules in Inelastic Electron Tunneling Spectroscopy

Published

October 16, 2008

Author(s)

J M. Beebe, H J. Moore, T R. Lee, James G. Kushmerick

Abstract

Determining the selection rules for the interaction of tunneling charge carriers with molecular vibrational modes is important for a complete understanding of charge transport in molecular electronic junctions. Here, we report the low-temperature charge transport characteristics for junctions formed from hexadecanethiol molecules having varying degrees of fluorination. Our results demonstrate that C-F vibrations are not observed in inelastic electron tunneling spectroscopy (IETS). Because C-F vibrations are almost purely dipole transitions, the insensitivity to fluorine substitution implies that Raman modes are preferred over infrared modes. Further, the lack of attenuation of the C-H vibrational modes with fluorine substitution suggests that either the scattering cross section is not an additive quantity or the physical position of a vibrational mode within the junction influences whether the transition is observed in IETS.

Citation

Nano Letters

Pub Type

Journals

Citation

Beebe, J. , Moore, H. , Lee, T. and Kushmerick, J. (2008), Vibronic Coupling in Semi-Fluorinated Alkanethiol Junctions: Implications for Selection Rules in Inelastic Electron Tunneling Spectroscopy, Nano Letters (Accessed October 11, 2025)